One way valves control the flow of blood within the heart. The mitral valve and tricuspid valve are referred to as the atrioventricular valves. The aortic valve and pulmonary valve are referred to as ventriculoarterial valves. Atrioventricular valves control the blood flow between the atria and the ventricle. The left atrioventricular valve is the mitral valve and the right atrioventricular valve is the tricuspid valve. Atrioventricular valves are comprised of an annulus, leaflets, and several chordae tendineae that connect the leaflets to the papillary muscles of their respective ventricles. Mitral valves have two leaflets and tricuspid valves have three leaflets. Ventriculoarterial valves control the blood flow between the ventricles and the two great arteries. The left ventriculoarterial or semilunar valve is the aortic valve and this separates the left ventricle and the aorta. The right ventriculoarterial or semilunar valve is the pulmonary (pulmonic) valve and this separates the right ventricle and the pulmonary artery.
The mitral valve is between the left atrium and the left ventricle of the heart. The mitral valve has two leaflets, an anterior leaflet and a posterior leaflet. The opening mitral valve annulus is a fibrous ring that surrounds the opening of the valve. The mitral valve regulates blood flow from the left atrium to the left ventricle and is a D-shaped annulus with two leaflets that extend into the left ventricle. The chordae tendineae connect the leaflets to the tips of the anterolateral and posteromedial papillary muscles.
The tricuspid valve is between the right atrium and right ventricle. The tricuspid valve regulates blood flow from the right atrium to the right ventricle and is an ovoid shape with three leaflets that extend into the right ventricle. Chordae tendineae extend from the three leaflets and connect to the three papillary muscles.
The pulmonary and aortic valves are referred to as the semilunar valves. Semilunar valves control blood flow between the ventricles and the great arteries. The pulmonary valve is between the right ventricle and the pulmonary artery. The aortic valve is between the left ventricle and the aorta.
In one type of heart valve dysfunction, a damaged, defective, or diseased heart valve may not be able to close properly and allow back flow of blood. This back flow is called regurgitation or incompetence. In this condition, a valve repair or replacement surgery may be performed. When the damage to an atrioventricular valve is less severe, valve repair in this specific situation may be possible. Valve repair involves placement of several sutures in the annulus of the atrioventricular valve and then securing a prosthetic ring in place to reduce the annular dimension and thus reduce the degree of valve incompetence. The prosthetic valve repair ring is constructed of a fixed length of cloth-like material to facilitate fixation of the material to the heart tissue by way of sutures.
In one type of heart valve dysfunction, valve stenosis, the flow area is decreased and blood flow through the valve is decreased. In stenosis, the damage to the valve tissue is often severe and due to calcific deposits or fibrosis. Though valve repair may be performed, valve replacement surgery is most commonly performed for this condition.
A damaged, defective, or diseased heart valve tissue is wholly or partially removed during valve replacement surgery in order to provide a sufficient orifice through which to secure the replacement valve. Replacement of heart valves may utilize prosthetic valves. Biologic valves are constructed out of harvested porcine valve tissue or bovine pericardium. Mechanical valves are constructed out of a metallic alloy. All replacement prosthetic valves have a sewing ring comprised of a cloth-like material to facilitate fixation of the prosthesis to the heart tissue by way of sutures.
In conventional valve replacement, the leaflets are wholly or partially removed and the annulus is circumferentially prepared by the separate insertion of multiple individual sutures. Following preparation of each of these sutures, they are separately inserted into the sewing ring of the prosthetic valve. The prosthetic valve is then lowered into the prepared orifice of the native valve. Then each of the individual sutures is separately tied to secure the valve. Each suture is then individually cut to complete the valve replacement.
The replacement of heart valves requires placement of many sutures. Each pair of suture ends is individually tied. Replacement valves may have a sewing ring that needs to be sewn to the annulus after the defective heart valve is removed. Placement of sutures is a time-consuming process. Curved needles may be used with the sutures to avoid inadvertent penetration of arteries or other structures.
Heart valve replacement surgery may take approximately 4 hours or longer. Historically, in a valve replacement operation, the patient is placed on cardiopulmonary bypass with the heart arrested. The patient is also under anesthesia for a prolonged period of time. A heart valve replacement surgery currently involves the following steps: 1) expose the valve, 2) resect the valve leaflet tissue, 3) place sutures through the annulus of the native tissue, 4) size the prosthesis, 5) place each individual stitch (10-20 pairs) through the sewing ring of the prosthesis, 6) lower the prosthesis and ring into the patient, 7) tie each pair of sutures, and 8) cut each pair of sutures. The number of sutures may range from 12 to over 25 and each is individually tied. A surgeon must be careful to not apply too much or too little tension on the sutures. A heart valve repair surgery currently involves all of the steps above except the valve leaflet tissue is not resected.
Various suturing or fastening apparatus have been developed. These apparatus include but are not limited to the apparatus disclosed in EP139180, U.S. Pat. No. 7,670,370, U.S. Pat. No. 5,417,700, US20040210305, US20060229675, WO2010065912, EP1511429, WO2008048846, WO2008058067, U.S. Pat. No. 6,997,932, and WO1997029694 all of which are incorporated by reference. Many suturing apparatus only place one suture at a time.
Methods or apparatus that can safely shorten the time required to perform replacement of a heart valve will be of benefit to patients and surgeons. In addition, methods and apparatus that will allow heart valve replacement to be done in a minimally invasive manner will also be beneficial. Invasive procedures increase the risk of infection, lengthen recovery time, and are more painful during recovery.